Live-line tools, also known in the industry as "hot sticks", are used by workers who must contact electrical equipment carrying high voltage. The live-line tool is constructed principally of a non-conducting material such as wood, fiberglass, or the like. Over time and use, however, the tool may become defective due to contamination with chemical substances or grime, mechanical damage, or absorption of moisture. When defective, the tool conducts electricity, placing the worker and the work site in danger. The risk of injury or fire hazard is increased by the fact that many of the work sites are outside, and thus exposed to inclement weather. Utility companies are at particular risk when trying to restore electrical service during thunderstorms, since water on the surface of a defective tool further increases the conductive potential.
Industries using live-line tools frequently have maintenance procedures to keep the tools clean and waxed to repel moisture. Care is taken to use nonabrasive cleaners leaving no conductive residue and to store the tool in dry surroundings. Still, it is sometimes difficult to determine if a tool is safe for use under field conditions by a simple surface examination. For example, visual examination of a tool will not always reveal a hairline crack that can retain moisture, thereby increasing conductivity of the tool dramatically.
The Occupational Safety and Health Administration (OSHA) has addressed the need for more definitive testing of live-line tools by adopting test standards almost identical to those previously promulgated in ASTM Specification 711. Recently adopted OSHA Maintenance Standard No. 1910.137 requires that a live-line tool be tested along its entire length every two years under both wet and dry conditions. After inspection, the tool is tested by applying 75,000 volts per foot of length for one minute for fiberglass tools and 50,000 volts per foot for one minute for a tool made of wood. A tool must also be tested if it has been repaired or refinished before it is reintroduced to service.
The live-line tool testers currently on the market, such as that manufactured by the Hannon company of Canton, OH, require that the tool be sent to the laboratory for testing. This is expensive and burdensome to industrial users, given the frequency of testing required by the new standards. Portable hand testers such as the model LS-80 manufactured by the A. B. Chance Co. may not meet the stringent new standards referenced above. There is, thus, a need in the industry for a tool tester that can accurately and safely perform these high voltage tests over the length of the tool at the work site instead of in a laboratory environment.